<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        button{
            background-color: brown;
            font-size: 50px;
        }
    </style>
</head>
<body>
    <button>按钮</button>
    <script>
        document.querySelector('button').onclick=function(){
            alert('点击了按钮')
        }
    </script>
</body>
</html>